The present invention relates to a washer pump for a washer device that sprays cleaning liquid to the windshield of a vehicle. More specifically, the present invention relates to a structure that protects the motor of the washer pump from water.
A typical washer device for vehicles includes a tank for storing cleaning liquid and a washer pump for pumping the cleaning liquid from the tank to a washer nozzle. The washer pump has a housing including a motor chamber and a pump chamber. The motor chamber accommodates a direct current motor. The pump chamber includes an impeller. The motor has an output shaft that extends into the pump chamber. The impeller is fixed to the distal end of the output shaft. A seal is located about the output shaft to seal the motor chamber from the pump chamber. The motor rotates the impeller, which pumps the cleaning liquid from the tank to the washer nozzle.
The temperature of the motor increases when operating and decreases when stopped. Air in the motor chamber expands or contracts in accordance with the changes of temperature of the motor. When the motor chamber is sealed, contraction of air in the motor chamber draws the cleaning liquid from the pump chamber to the motor chamber between the output shaft and the seal. This may cause the motor to corrode and malfunction.
To solve the above problems, Japanese Unexamined Utility Model Publication No. 2-49657 describes a washer pump having an air hole open to the atmosphere. As shown in FIG. 7, a cylindrical washer pump 60 is attached to a side of a tank 63, which stores window cleaning liquid. A housing 64 of the pump 60 includes a motor case 70 and a pump case 67 attached to the lower part of the motor case 70. A motor chamber 66 for accommodating a motor 61 is formed in the motor case 70. A pump chamber 65 for accommodating an impeller 73 is formed between the motor case 70 and the pump case 67.
An output shaft 62 of the motor 61 extends vertically through the motor case 70 to the inside of the pump chamber 65. A seal 72 is located about the output shaft 62 to seal the motor chamber 66 from the pump chamber 65. The motor case 70 has an inlet 68 for introducing cleaning liquid from the tank 63 to the pump chamber 65. The pump case 67 has an outlet 69 for discharging cleaning liquid from the pump chamber 65. An air hole 71 connects the motor chamber 66 to the outside of the housing 64 near the lower end of the motor case 70 below the motor 61.
The air hole 71 prevents cleaning liquid from being drawn from the pump chamber 65 to the motor chamber 66. Even if cleaning water enters the motor chamber 64 due to a defect of the seal 72, the air hole 71 drains the cleaning liquid to the exterior of the motor chamber 66 and prevents the cleaning liquid from contacting the motor 61.
However, if the washer pump 60 is splashed by water while the vehicle runs through standing water, water may get in the motor chamber 66 through the air hole 71. This may cause a malfunction of the motor 61 and thus should be avoided.
Condensation of water may also occur due to temperature changes of the motor 61. The air hole 71 is not suitable for removing water condensation.
Further, most of the washer pump 60 is located outside the tank 63. This complicates the attachment of the washer pump 60 to the tank 63 and causes the washer pump 60 to be unstable.
It is possible to form a recess on a side wall of the tank 63 and fix the washer pump 60 in the recess with fasteners. However, this complicates the shape of the tank 63 and the installation of the pump 60. Also, this limits the shape of the tank 63, which complicates the tank 63 installation.
As shown in FIG. 8, Japanese Unexamined Patent Publication 4-129863 describes a washer pump 80, half of which is received in and fixed to a tank 81. A housing 82 of the pump 80 extends horizontally. An inlet 84 connected to a pump chamber 83 is formed in the distal end of the housing 80, which is located in the tank 81. A motor chamber is horizontally spaced from the pump chamber 83. The motor 86 rotates an impeller 87, which causes cleaning liquid in the tank 81 to flow through the inlet 84, a passage 88 in the housing 82, and through an outlet (not shown).
The pump 80 is received in and firmly fixed to the tank 81 without a complicated installation structure. Therefore, the shape of the tank 81 is simple and not limited.
However, since the motor chamber 85 is horizontally spaced from the pump chamber 83, if cleaning water in the pump chamber 83 enters the motor chamber 85, the horizontal motor 86 in the motor chamber 85 is immediately exposed to the leaked cleaning liquid. Even if an air hole that can drain the leaked cleaning liquid is provided in the motor chamber 85, the leaked cleaning liquid from the pump chamber will most likely contact the motor 86 before being drained. Therefore, in the pump 80 of FIG. 8, an air hole alone will not prevent the motor 86 from contacting cleaning liquid.